The purpose of the present study is to demonstrate the involvement of the basal ganglia, especially the nigrostriatal dopamine (DA) pathway, in the generation of the masticatory and locomotive movements using animal models of hemi-Parkinson's disease.Unilateral lesions in the nigrostriatal dopamine (DA) pathway were made in male Sprague-Dawley rats by microinjection of 6-hydroxydopamine (8mug/4 mu1/8 min) into the substantia nigra.Locomotive imbalances following these lesions were assessed by counting full rotations per min toward the lesioned side, in a cylindrical container at 10-min interval for the first 60 min after methamphetamine (MET ; 3mg/kg, i.p.) injection.Rats which showd more than 10 turns/min were judged and used as animal models of hemi-Parkinson's disease.Video-camera and electro-myograph (EMG) were used to analyze precisely movements of the foreleg and lower jaw during MET-induced rotational behavior.The surface EMGs were recorded from the brachial tricep muscle and the jaw-opening (anterior digastric) and jaw-closing (masseter) muscles on the both sides.Acute experiments were also performed in anesthetized model rats with C2 transection, mounted on a stereotaxic frame under artificial respiration.MET was injected and jaw movements were evoked to analyzed by means of the EMG and a gnathodynamic recorder.From the above experiments, it was elucidated that the activation of the nigrostriatal dopamine pathway by MET injection resuted in the production of the masticatory and locomotive movements in the rat.